This invention relates to computer systems. The invention is particularly, although not exclusively, concerned with a Human-Computer Interface (HCI); that is, to a mechanism for providing an interface between a computer system and a human user.
Most present day business applications use a linear flow processing model. The essential characteristic of design methodologies for such models is hierarchic decomposition. In other words, an application is decomposed into its major subsystems, which are in turn decomposed into smaller and smaller elements.
A consequence of the tools associated with this model is that the Human-Computer Interface (HCI) follows the same hierarchic decomposition. Typically, HCI screens reside at the lowest levels of the hierarchy, with menu selection used to navigate the various levels of the hierarchy. The number of alternative actions available at any point is therefore low, and there is usually only a single way of navigating between one point and another. There is also only a single context--it is not normally possible to leave a partially completed screen and return to it with the data left as it was.
Modern HCI tools, on the other hand, typically are based on an event driven processing model. The natural underlying design methodology is object oriented. Such HCIs are usually non-linear. In other words, the order in which actions are performed is not predetermined: leaving a partially completed screen in order to do something else, and returning to where it was left off is allowed for. Alternative navigation paths are also allowed for, and the number of choices at any particular point tends to be large.
Many companies are dissatisfied with the HCIs that are provided by their enterprise-wide applications, in which they have spent millions of pounds, particularly when applications costing a few hundred pounds, which exhibit the qualities of modern HCIs, abound on personal computers.
The object of the present invention is to provide a bridge between processing components based on a linear-flow processing model, and processing components based on non-linear processing models, such as object-oriented models.